F. X. Malcata

Microalgae as sources of carotenoids.

Marine microalgae constitute a natural source of a variety of drugs for pharmaceutical, food and cosmetic applications—which encompass carotenoids, among others. A growing body of experimental evidence has confirmed that these compounds can play important roles in prevention (and even treatment) of human diseases and health conditions, e.g., cancer, cardiovascular problems, atherosclerosis, rheumatoid arthritis, muscular dystrophy, cataracts and some neurological disorders. The underlying features that may account for such favorable biological activities are their intrinsic antioxidant, anti-inflammatory and antitumoral features. In this invited review, the most important issues regarding synthesis of carotenoids by microalgae are described and discussed—from both physiological and processing points of view. Current gaps of knowledge, as well as technological opportunities in the near future relating to this growing field of interest, are also put forward in a critical manner.

Invited review: Physiological properties of bioactive peptides obtained from whey proteins

Processing of whey proteins yields several bioactive peptides that can trigger physiological effects in the human body: on the nervous system via their opiate and ileum-contracting activities; on the cardiovascular system via their antithrombotic and antihypertensive activities; on the immune system via their antimicrobial and antiviral activities; and on the nutrition system via their digestibility and hypocholesterolemic effects. The specific physiological effects, as well the mechanisms by which they are achieved and the stabilities of the peptides obtained from various whey fractions during their gastrointestinal route, are specifically discussed in this review.

Anti-Inflammatory Activity of Chitooligosaccharides in Vivo

All the reports to date on the anti-inflammatory activity of chitooligosaccharides (COS) are mostly based on in vitro methods. In this work, the anti-inflammatory activity of two COS mixtures is characterized in vivo (using balb/c mice), following the carrageenan-induced paw edema method. This is a widely accepted animal model of acute inflammation to evaluate the anti-inflammatory effect of drugs. Our data suggest that COS possess anti-inflammatory activity, which is dependent on dose and, at higher doses, also on the molecular weight. A single dose of 500 mg/kg b.w. weight may be suitable to treat acute inflammation cases; however, further studies are needed to ascertain the effect upon longer inflammation periods as well as studies upon the bioavailability of these compounds.

Evaluation of antimicrobial edible coatings from a whey protein isolate base to improve the shelf life of cheese

The objective of this work was to evaluate the effectiveness of antimicrobial edible coatings to wrap cheeses, throughout 60 d of storage, as an alternative to commercial nonedible coatings. Coatings were prepared using whey protein isolate, glycerol, guar gum, sunflower oil, and Tween 20 as a base matrix, together with several combinations of antimicrobial compounds-natamycin and lactic acid, natamycin and chitooligosaccharides (COS), and natamycin, lactic acid, and COS. Application of coating on cheese decreased water loss (~10%, wt/wt), hardness, and color change; however, salt and fat contents were not significantly affected. Moreover, the antimicrobial edible coatings did not permit growth of pathogenic or contaminant microorganisms, while allowing regular growth of lactic acid bacteria throughout storage. Commercial nonedible coatings inhibited only yeasts and molds. The antimicrobial edible coating containing natamycin and lactic acid was the best in sensory terms. Because these antimicrobial coatings are manufactured from food-grade materials, they can be consumed as an integral part of cheese, which represents a competitive advantage over nonedible coatings.

Chitosan: antimicrobial action upon staphylococci after impregnation onto cotton fabric

Background:  High levels of viable Staphylococcus aureus, which are often found on inflamed skin surfaces, are usually associated with atopic dermatitis. Textiles, owing to their high specific surface area and intrinsic hydrophilicity, retain moisture while also providing excellent environmental conditions for microbial growth and proliferation. Recently, a number of chemicals have been added to textiles, so as to confer antimicrobial activity.

Characterization of whey cheese packaged under vacuum.

Vacuum packaging was assayed at 4 degrees C and was tested in comparison to unpackaged counterparts, in both microbiological and physicochemical terms, in studies pertaining to the preservation of Requeijão, a traditional Portuguese whey cheese. Bacteria were absent (i.e., <10 CFU/g) in whey cheeses on the day of manufacture as a result of thermal processing. After storage, both unpackaged and packaged cheeses exhibited high viable counts of Bacillus, Pseudomonas, Enterobacteriaceae, and lactic acid bacteria (especially lactococci). Yeasts, staphylococci, enterococci, and spore-forming clostridia were severely inhibited by the package vacuum combined with the increasing acidification developed therein. Whey cheeses packaged under vacuum underwent substantial acidification, slight depletion of lactose, and no significant variation in moisture content or texture; conversely, unpackaged whey cheeses exhibited substantial loss of water and a concomitant increase in rigidity. Vacuum packaging strongly inhibited lipolysis (even if viable counts of some microbial groups were high); saturated fatty acids (mainly C16:0 and C14:0) accounted for ca. 73% of the total free-fatty acid content, whereas the most concentrated unsaturated fatty acids were C18:1 and C18:2 (ca. 14% each). The conclusions generated in our study are, in general, useful for a wide range of whey cheeses worldwide: i.e., Requéson (Spain), Ricotta (Italy), Broccio (France), and Anthotyro (Greece). In addition, our conclusions are particularly helpful in terms of improving the safety of Requeijão, a widely acclaimed dairy specialty.

Evaluation of the Antioxidant Activity of Cell Extracts from Microalgae

A growing market for novel antioxidants obtained from non-expensive sources justifies educated screening of microalgae for their potential antioxidant features. Characterization of the antioxidant profile of 18 species of cyanobacteria (prokaryotic microalgae) and 23 species of (eukaryotic) microalgae is accordingly reported in this paper. The total antioxidant capacity, accounted for by both water- and lipid-soluble antioxidants, was evaluated by the (radical cation) ABTS method. For complementary characterization of cell extracts, a deoxyribose assay was carried out, as well as a bacteriophage P22/Salmonella-mediated approach. The microalga Scenedesmus obliquus strain M2-1 exhibited the highest (p > 0.05) total antioxidant capacity (149 ± 47 AAU) of intracellular extracts. Its scavenger activity correlated well with its protective effects against DNA oxidative damage induced by copper(II)-ascorbic acid; and against decay in bacteriophage infection capacity induced by H2O2. Finally, performance of an Ames test revealed no mutagenic effects of the said extract.

Use of small ruminants’ milk supplemented with available nitrogen as growth media for Bifidobacterium lactis and Lactobacillus acidophilus

Growth of, and acid production by Bifidobacterium lactis and Lactobacillus acidophilus using ovine and caprine milk as media were evaluated for their potential use in cheese‐making. A protein hydrolysate (MHP, obtained from incubation of bovine milk with protease) or a mixture of free amino acids (FAA, similar to the amino acid fraction of MHP) was added as a nitrogen enrichment source. Bifidobacterium lactis and Lact. acidophilus were inoculated at 50 ml l−1 and incubated at 37 °C with growth supplements added at ratios in the range 25–50 ml l−1. The maximum viable counts of Bif. lactis were lower in plain ovine and caprine milk than in nitrogen‐enriched milk, and MHP was a better growth promoter than FAA. A similar trend was observed with the acidity values developed, and attempts to correlate growth with acidity were successfully performed. The highest uptake rates of amino acids in ovine milk were observed for lysine, isoleucine, leucine and proline, but only isoleucine was taken up at a similar rate in caprine milk. Final bacterial viable counts of Lact. acidophilus in the plain and enriched forms of ovine milk did not differ greatly from each other, although FAA was statistically a better growth promoter than MHP. Unlike results in ovine milk, cultures of Lact. acidophilus in caprine milk exhibited drops of 1–1·5 log cycles in viable cell counts by 24 h of fermentation, irrespective of the nature of the nitrogen source. Parallel studies indicated that the excess of fatty acid residues in caprine milk could be responsible for the poor growth of Lact. acidophilus.

Manufacturing of fermented goat milk with a mixed starter culture of Bifidobacterium animalis and Lactobacillus acidophilus in a controlled bioreactor

Aims:  This work was undertaken to study the feasibility and the characteristics of a fermented product made of goat milk, using a mixed starter culture of Bifidobacterium animalis and Lactobacillus acidophilus under controlled conditions, and to determine their survival in the fermented milk during refrigerated storage.

Characterization of Requeijão and technological optimization of its manufacturing process

Abstract In attempts to characterize Portuguese whey cheese (Requeijao) and optimize the manufacture thereof, 17 whey cheeses were produced according to a factorial design using heating time, heating temperature and fractional addition of ovine/caprine milk as manipulated technological variables. Chemical analyses were carried out for the 17 cheeses, whereas sensorial and rheological analyses were carried out for eight selected whey cheeses and a reference (i.e. a whey cheese produced locally according to traditional procedures). A true local maximum exists for moisture content (at a temperature of about 93 °C, heating time of about 30 min and addition of about 17% ovine milk) which lies well within the range chosen for experimentation. Fat content of Requeijao was positively affected by heating temperature (especially via its quadratic effect) and, to a lesser extent, by heating time (especially via its linear effect); nitrogen content was especially affected by heating temperature (via its quadratic effect); and moisture content was affected especially by heating temperature (via its quadratic effect). The sensorial analyses showed that the eight whey cheeses produced were preferred with respect to the reference whey cheese. For rheological analyses the most significant observations pertain to the high strain dependence of the dynamic moduli, absence of a true equilibrium storage modulus, and relatively low difference between the loss and the storage modulus.